[pt] O presente estudo parte da premissa de que novas formas de se comunicar surgem ao longo dos anos, inclusive na relação entre o humano e a máquina, onde, atualmente, a fala é o veículo comunicacional predominante. E nesse diálogo há uma busca para a adequação da máquina à nossa forma de comunicação e uma constante necessidade de adequação dos seres humanos à forma de comunicação da máquina. Essa investigação visa elucidar se sistemas baseados em interfaces de voz compõe o modelo de interação fundado no que se define como conversa, sendo amparados pelas áreas da ergonomia e usabilidade e por fundamentos provenientes da teoria da conversação. Este trabalho encontra-se estruturado em quatro seções: a primeira equivale a fundamentação teórica; a segunda seção abrange o levantamento de dados através de entrevistas com usuários de interfaces conversacionais; a terceira seção constitui-se na análise de conteúdo das entrevistas; e por fim, a quarta seção envolve as considerações em torno das experiências no uso de interfaces conversacionais atuais. / [en] The present study starts from the premise that new ways of communication are emerging throughout the years, including the relationship between human and machine, which nowadays, speech is the predominant communicational vehicle. And in this dialogue, there is a search for the adaptation of the machine to our form of communication and a constant need to human s adaptation to the machine s form of communication. This investigation attempts to clarify if systems based on voice interfaces are in fact composed by a model of interaction that is defined as conversation, and if they are actually being supported by the areas of ergonomics, usability, and also by the basics fundaments of conversation theory. This work finds itself structured in four sections: the first one corresponds to the theoretical foundations; the second section embraces data collection, which gathered several interviews with the users of conversational interfaces; the third section is established on the content analysis of the previous interviews; lastly, the fourth section concerns the final considerations of the current experience of conversational interfaces.

This thesis focuses on analysis, definition and description of mobile personal assistants as a phenomenon emerging in past few years. Mobile personal assistants are first mentioned in the context of computational linguistics and information needs, which is one of the motivations to use them. Main interest of this thesis is an introduction of the core technologies for the natural language communication between the assistant and its user, followed by an introduction of host environments and possible usage. The thesis also presents the limitations and risks resulting from using them, which are in some ways affecting their usability. Beside the analysis the main focus is on the design and implementation of the natural language understanding (NLU) system, which can be used in particular personal assistant application. This system is implemented as a web service and consists of an annotation scheme with a set of components. The results show that the system architecture and tools used are suitable solution for the construction of a basic NLU system, which has been created and which is in the compliance with the requested parameters. It is still difficult task to achieve high precision, which depends on many factors including the amount of training data, which was very small in this case. However, the resulting application is a solid starting point for its further development and extensions.